There are a wide variety of available level mechanisms for indicating when a surface on which a straight edge of the level mechanism is placed is horizontal, and allowing relative rotation between a level tube of the level mechanism and the level mechanism frame to provide any desired angular orientation therebetween. See U.S. Pat. No. 2,692,440 (the disclosure of which is hereby incorporated by reference herein). While such level mechanisms are useful, they have some limitations, especially in the machine tool environment. For instance, in utilizing such conventional level mechanisms to orient a workpiece with respect to a drill press, or the like, with a predetermined annular relationship between the drill press and workpiece being desired, if the work surface for the drill press is not truly horizontal the workpiece will be improperly positioned if the degree indicia on the level mechanism are relied upon. Therefore, a complicated procedure must be gone through to take into account the particular amount that the machine tool working surface deviates from the horizontal, otherwise the proper annular orientation of the workpiece with respect to the drill press wil not be achieved.
According to the present invention a level mechanism is provided that overcomes the drawbacks inherent in prior level mechanisms, especially in the machine tool environment. By utilizing the level mechanism according to the present invention, and practicing the method of setting up a workpiece with respect to the machine tool, it is possible to accurately positively position a workpiece with respect to a machine tool at a desired angular orientation in a simple manner.
The level mechanism according to the present invention comprises a frame including an elongated straight edge portion; a spirit level tube; a first annular member having first indicia formed thereon; a second annular member having second indicia formed thereon for cooperation with the first indicia; first actuator means for grasping to effect rotation of the first annular member; and second actuator means distinct from the first actuator means for grasping to effect rotation of the second annular member. The level mechanism further includes means for mounting the level tube with respect to the first and second annular members and for mounting the first and second annular members with respect to the frame, so that the first annular member is rotatable (about an axis perpendicular to the straight edge) with respect to the frame with the second annular member and the level tube being rotatable therewith upon actuation of the first actuator means, so that no relative movement between the first and second indicia takes place but the operative orientation of the level tube with respect to the frame straight edges changes; and so that the level tube is rotatable (about the same axis) with respect to the first annular member upon actuation of the second actuator means, so that relative movement between the first and second indicia takes place and the operative orientation of the level tube with respect to the frame straight edge changes; so that the level tube is readable.
The means for mounting the level tube with respect to the first and second annular members in the frame includes defining a circular bore in the frame perpendicular to the direction of elongation of the straight edge and coaxial with the axis of rotation of the annular members and having a first bearing surface; means defining a second bearing surface on the first annular member for operatively engaging the first bearing surface; means for defining a third bearing surface on the first annular member; and means defining a fourth bearing surface on the second annular member for operatively engaging the third bearing surface. The mounting means further comprises a level tube mounting mechanism including a hub portion for extending into the frame circular bore and constructed so that some operative engagement between the first annular member and the hub takes place so that they may rotate together when the first actuator means is actuated; and means for rigidly fixing the second annular member to the level tube mounting mechanism. The level tube mounting means includes a rim portion having a diameter larger than the diameter of bore, and the means for fixing the second annular member to the level tube mounting mechanism includes a plurality of screws passing through the bore from the level tube mounting means rim to the second annular member to threadably engage the same.
The straight edge preferably has an involute curve configuration along the length thereof. The first annular member preferably has gear teeth formed along the exterior periphery thereof and the first actuating means comprises a gear member operatively mounted to the frame for rotative movement with respect thereto and operatively engaging the gear teeth of the first annular member. The second actuator means comprises a tubular member standing proud of the second annular member with the spirit level tube being readable through the tubular member. The second indicia preferably comprises indicia markings corresponding to each degree from 1 to 90 degrees along the periphery of a quadrant of the second annular member, and the first indicia means preferably comprise a vernier disposed along a portion of the first annular member for cooperation with the second indicia means, one indicia line on the vernier scale being parallel to the straight edge. Further, if desired, locking means may be provided for locking the first annular member in a particular position to which it has been rotated with respect to the frame, and locking means maybe provided locking the second annular in a particular position to which it has been rotated with respect to the frame.
According to another aspect of the present invention, a level mechanism is provided comprising a frame having an elongated straight edge and a circular bore extending therethrough having an axis perpendicular to the straight edge; a first annular member mounted coaxially with the bore and received at least in part within the bore; a second annular member coaxial with the first annular member and received at least in part within the first annular member; and the spirit level tube. A mechanism further comprises a third annular member coaxial with the bore and having a rim portion and a hub portion standing proud from the rim portion, the hub portion received at least in part within the first annular member and the bore and supporting the level tube, and the rim portion having a diameter larger than the diameter of the circular bore, the rim portion abutting the frame. A plurality of fasteners are provided for affixing the third annular member to the second annular member.
A method according to the present invention for setting up a workpiece for a machine tool or the like having a generally horizontal work surface is provided, utilizing a level mechanism including a spirit level tube which indicates the coincidence with the horizontal of a straight edge of the level mechanism. The method comprises the following steps: Placing the mechanism straight edge on the machine tool work surface. Adjusting the angular orientation of the level tube with respect to the mechanism straight edge until the level tube bubble is centered, centering being at a first position. Rotating the level tube with respect to the mechanism straight edge an angle a from the first position, the angle a corresponding to the desired angular orientation of a workpiece with respect to a horizontal. Placing the mechanism straight edge on the workpiece; and adjusting the position of the workpiece until the level tube bubble is centered without changing the angular orientation of the level tube with respect to mechanism straight edge, and maintaining the workpiece in place once the level bubble is centered. The machine tool preferably is a drill press having a generally vertically extending drill bit path of movement (the drill bit path of movement being perpendicular to the work surface of the drill press) and the workpiece maintaining step is preferably practiced by clamping the workpiece in place with a vise.
It is the primary object of the present invention to provide a level mechanism and method of utilization thereof that provide for accurate positioning of a workpiece with respect to a machine tool in a simple manner, even if the machine tool work surface is not completely horizontal. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.